Mumbai Metro Lines 4 and 6 still unfinished eight years on, as Line 5 moves ahead

The question of which project will earn the title of Mumbai's most delayed metro is now being asked. Green Line 4 (Wadala-Thane) and Pink Line 6 (Swami Samarth Nagar-Vikhroli) are running neck and neck in this race, and neither appears set to open soon. Orange Line 5 (Thane-Bhiwandi-Kalyan) meanwhile seems to be moving ahead quickly, especially its first phase.

Construction began about eight years ago, but passenger services have not started on either Line 4 or Line 6. Land acquisition hurdles, incomplete stations, depot-related tangles and repeatedly extended deadlines have left commuters waiting for relief from traffic jams.

Both elevated corridors were meant to ease east-west and north-south travel in Mumbai's suburbs. Together they run 47.63 km, have 43 stations and have a published project cost of Rs 21,265 crore. Construction began around 2018, but slow progress on key stretches has caused repeated delays.

According to the MMRDA's progress report of August 31, 2026, 95 per cent of the pier work, 94 per cent of the U-girder installation and 92 per cent of the deck-slab work on Green Line 4 is complete. These figures reflect progress on separate construction packages, not readiness of the whole line to open.

For Green Line 4, a 16,762 sq m plot at Laxmi Nagar in Vikhroli East remained stuck for years. After prolonged negotiation and legal proceedings, the MMRDA got possession in March 2026. The acquisition cost about Rs 164.31 crore. Pink Line 6 faced obstacles at the Shyam Nagar station, the JVLR-Eastern Express Highway junction and the proposed Kanjurmarg depot. On September 29, 2026, the Supreme Court dismissed a developer's appeal against the Bombay High Court's February 13 ruling on the 15-hectare Kanjurmarg depot plot. This cleared the way for the long-stalled depot. Court proceedings also showed that, up to the period stated in an affidavit, the MMRDA had spent Rs 2,293.12 crore on Line 6.

Trial runs on the northern Green Line 4/4A section began in September 2025 with a flag-off. However, commercial service could not start because the station structures were incomplete and safety-related conditions remained. The proposed partial opening was earlier due in early 2026, but was later reported to have slipped to November 2026.

Orange Line 5, on the other hand, appears to be pulling ahead. In 18 months of construction, which began in 2020, 200 U-girder spans have been installed. Civil work on the first phase from Thane to Dhamankar Naka in Bhiwandi is complete. The first rake, borrowed from Metro Lines 2A and 7 through the Kasarvadavali interchange, has reached the site, and trial runs are under way to test the 25 kV overhead power supply and the signalling system. When operational, Line 5 will connect with Green Line 4 (Wadala-Thane), the extended Orange Line 12 (Kalyan-Taloja) and Central Railway.

The MMRDA has projected daily ridership of 12.13 lakh on Green Line 4 and 7.69 lakh on Pink Line 6 by 2031. Both lines are expected to improve suburban connectivity and cut travel time. But the repeated change of dates has raised questions about the project's planning, coordination and accountability. Elevated tracks and stations are rising in the city's skyline, but commuters are still waiting for the promised service.

Transport expert Arindam Mahapatra said: "A metro corridor in Mumbai takes eight to ten years to build from scratch, on average. Lines 4 and 6 are among the slowest, but I would regard Line 6 as the more delayed project. Titagarh has not yet delivered its trains and several viaduct gaps remain to be joined with girders. Line 4 is in a better position, with train deliveries expected by the end of the year, which would make the rakes ready for revenue service. Line 4 does not have its own carshed either, but if Mogharpada is delayed, Line 5's Kasheli depot is its backup, which Line 6 does not have at present. Besides, there is a continuous viaduct from Gaimukh to the Shangrila in Bhandup, which is the next reversal point after the Cadbury junction. Once civil work is done, the MMRDA can extend service beyond Cadbury. By comparison, Metro Line 12 has moved at a pace like Line 5's, with 200 U-girder spans installed in just 18 months of construction."

Metro enthusiast Shubham Padave said: "I think Line 6 may win the race for Mumbai's most delayed metro project in the end, because many parallel infrastructure works linked to this corridor are still incomplete. The unresolved carshed issue and the parallel Jogeshwari flyover project are big worries. But the bigger question is whether Line 6 will break the Navi Mumbai Metro's record, which took more than 12 years to complete just 11.1 km and 11 stations."